Damper device

ABSTRACT

A damper device is disposed between an engine and a transmission and has a torque distribution mechanism that is provided with a first input element connected to the engine, a second input element connected to the engine via an elastic member, a first output element connected to the transmission, and a second output element connected to the transmission. The damper device further has a first clutch that is disposed between the first output element and the transmission, and is switched between an engaged state of connecting the first output element to the transmission and a released state of disconnecting the first output element from the transmission, and a second clutch that is disposed between the second output element and the transmission, and is switched between an engaged state of connecting the second output element to the transmission and a released state of disconnecting the second output element from the transmission.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a Divisional Application of U.S. patentapplication Ser. No. 14/197,083, filed on Mar. 4, 2014, which is basedon and claims priority from Japanese Patent Application No. 2013-050699filed on Mar. 13, 2013 and Japanese Patent Application No. 2013-050705filed on Mar. 13, 2013, the entire contents of which is incorporatedherein by reference.

BACKGROUND

1. Technical Field

The present invention relates to a damper device disposed between anengine and a transmission.

2. Related Art

A damper device is disposed between an engine and a transmission inorder to reduce torsional vibration that is transmitted from the engineto the transmission. For example, a damper device has been proposed thatincludes two flywheels connected to each other via a spring (see PCTInternational Publication No. WO 2012/66680). The connection of the twoflywheels via the spring can suppress the torsional vibration of theengine.

Damper devices are designed so as to exclude a resonance point (naturalfrequency) of the damper device from a normal region of enginerevolutions, through adjustment of the mass and spring constant of thevarious members that make up the damper device. Through mere adjustmentof masses and spring constants in the damper device, however, it isdifficult to exclude the resonance point of the damper device from awide region, extending from a low-revolutions region to ahigh-revolutions region. Accordingly, it is difficult to suppresstorsional vibration of the engine over a wide region in cases whereconventional damper devices are used.

SUMMARY OF THE INVENTION

The present invention has been designed in consideration of thecircumstances described above, and an object thereof is to suppressengine torsional vibration over a wide region.

An aspect of the present invention provides a damper device that isdisposed between an engine and a transmission, the damper device having:a torque distribution mechanism including a first input elementconnected to the engine, a second input element connected to the enginevia an elastic member, a first output element connected to thetransmission, and a second output element connected to the transmission;a first clutch that is disposed between the first output element and thetransmission, and that is switched between an engaged state ofconnecting the first output element to the transmission and a releasedstate of disconnecting the first output element from the transmission;and a second clutch that is disposed between the second output elementand the transmission, and that is switched between an engaged state ofconnecting the second output element to the transmission and a releasedstate of disconnecting the second output element from the transmission.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating a power unit that is providedwith a damper device, which is a first implementation of the presentinvention;

FIG. 2 is an explanatory diagram illustrating a structure model of thedamper device built into the power unit;

FIG. 3A and FIG. 3B are explanatory diagrams illustrating instances oftransmission of engine torque;

FIG. 4 is an image diagram illustrating a damping characteristic oftorsional vibration by the damper device;

FIG. 5 is an explanatory diagram illustrating a control state of a firstclutch and a second clutch;

FIG. 6 is a schematic diagram illustrating a power unit that is providedwith a damper device, which is a second implementation of the presentinvention;

FIG. 7 is an explanatory diagram illustrating a structure model of thedamper device built into a power unit;

FIG. 8A and FIG. 8B are explanatory diagrams illustrating instances oftransmission of engine torque;

FIG. 9 is an image diagram illustrating a damping characteristic oftorsional vibration by the damper device;

FIG. 10 is an explanatory diagram illustrating a control state of afirst clutch and a second clutch;

FIG. 11 is a schematic diagram illustrating a power unit that isprovided with a damper device, which is another implementation of thepresent invention;

FIG. 12 is an image diagram illustrating a damping characteristic oftorsional vibration by the damper device;

FIG. 13 is an explanatory diagram illustrating a control state of afirst clutch and a second clutch;

FIG. 14 is a schematic diagram illustrating a power unit that isprovided with a damper device, which is another implementation of thepresent invention; and

FIG. 15 is a schematic diagram illustrating a power unit that isprovided with a damper device, which is another implementation of thepresent invention.

DETAILED DESCRIPTION

Implementations of the present invention are explained in detail nextwith reference to accompanying drawings. FIG. 1 is a schematic diagramillustrating a power unit 10 comprising a damper device, which is afirst implementation of the present invention. FIG. 2 is an explanatorydiagram illustrating a structure model of a damper device 11 that isbuilt into the power unit 10. FIG. 3A and FIG. 3B are explanatorydiagrams illustrating instances of transmission of engine torque. Asillustrated in FIG. 1, the power unit 10 has an engine 12, being aninternal combustion engine, and a transmission 13 that is connected tothe engine 12 via a damper device 11. Thus, the damper device 11 isdisposed between the engine 12 and the transmission 13, such thattorsional vibration derived from vibration forces of the engine 12 isdamped by the damper device 11. As used herein, the term torsionalvibration of the engine 12 denotes torque variation derived from, forinstance, unbalanced inertial forces and combustion vibration forcesthat act upon a crankshaft 21 of the engine 12. A drive wheel 14 isconnected to the transmission 13 via a differential device notillustrated, and so forth.

As illustrated in FIG. 1 and FIG. 2, the damper device 11 comprises atorque distribution mechanism (planetary gear mechanism) 20 made up of acompound planetary gear train. The torque distribution mechanism 20comprises a carrier (first input element) C connected with thecrankshaft 21, and a first ring gear (second input element) R1 connectedto the crankshaft 21 via a spring (elastic member) 22. An inertia member23 having a predetermined mass is fixed to the first ring gear R1 thatis connected to the crankshaft 21 via the spring 22. The torquedistribution mechanism 20 comprises a second ring gear (first outputelement) R2 connected to the transmission 13, and a sun gear (secondoutput element) S that is connected to the transmission 13. Further, acompound pinion gear CP, having a first pinion gear P1 and a secondpinion gear P2 integrally formed with each other, is rotatably providedin the carrier C. The first pinion gear P1 meshes with the first ringgear R1, and the second pinion gear P2 meshes with the second ring gearR2 and the sun gear S.

The torque distribution mechanism 20 is provided with two input paths 24and 25, through which the engine torque is inputted, and two outputpaths 26 and 27 through which the engine torque is outputted.Specifically, the torque distribution mechanism 20 is provided with afirst input path 24 through which the engine torque is inputted to thecarrier C, and with a second input path 25 through which the enginetorque is inputted to the first ring gear R1 via the spring 22. Thetorque distribution mechanism 20 is provided with a first output path 26through which the engine torque is outputted from the second ring gearR2, and with a second output path 27 through which the engine torque isoutputted from the sun gear S.

A first clutch CL1 that is switched between an engaged state and areleased state is provided between the second ring gear R2 and thetransmission 13. Thus, the second ring gear R2 becomes connected to thetransmission 13 through switching of the first clutch CL1 to the engagedstate, and the second ring gear R2 becomes disconnected from thetransmission 13 through switching of the first clutch CL1 to thereleased state. In the case where the first clutch CL1 is switched tothe engaged state, as illustrated in FIG. 3A, engine torques T1 and T2that are distributed over the first input path 24 and the second inputpath 25 are combined via the torque distribution mechanism 20, andthereafter, the engine torques T1 and T2 are outputted through thesecond ring gear R2 and the first output path 26 to the transmission 13.Herein, the distribution ratio between the engine torque T1 and theengine torque T2 for canceling out the torque variation of the enginetorque T1 is set on the basis of the number of teeth of the first ringgear R1, the first pinion gear P1, the second pinion gear P2 and thesecond ring gear R2.

Similarly, a second clutch CL2 that is switched between an engaged stateand a released state is provided between the sun gear S and thetransmission 13. The sun gear S becomes connected to the transmission 13through switching of the second clutch CL2 to the engaged state, and thesun gear S becomes disconnected from the transmission 13 throughswitching of the second clutch CL2 to the released state. In a casewhere the second clutch CL2 is switched to the engaged state, asillustrated in FIG. 3B, the engine torques T1 and T2 that aredistributed over the first input path 24 and the second input path 25are combined via the torque distribution mechanism 20, and thereafter,are outputted through the sun gear S and the second output path 27 tothe transmission 13. Herein, the distribution ratio between the enginetorque T1 and the engine torque T2 for canceling out the torquevariation of the engine torque T1 is set on the basis of the number ofteeth of the first ring gear R1, the first pinion gear P1, the secondpinion gear P2 and the sun gear S.

As illustrated in FIG. 1, a control unit 30 that functions as a clutchcontroller is provided in the power unit 10, with a view to controllingthe first clutch CL1 and the second clutch CL2 of the damper device 11.The power unit 10 is provided with a valve unit 31 that comprises aplurality of electromagnetic valves, and with an oil pump 32 that pumpshydraulic oil towards the valve unit 31. An engine revolutions sensor 33that detects a rotational speed (hereafter notated as enginerevolutions) of the crankshaft 21 is connected to the control unit 30.The control unit 30 selects, on the basis of engine revolutions detectedby the engine revolutions sensor 33, the clutch CL1 or CL2, whichever isto be switched to the engaged state, and outputs a control signal to thevalve unit 31. Specifically, the control unit 30 switches the firstclutch CL1 or the second clutch CL2 to the engaged state, on the basisof engine revolutions, and selects thereby the output path 26 or 27 forextracting the engine torque. The control unit 30 is made up of, forinstance, a CPU that computes control signals and the like, a ROM thatstores a control program, arithmetic expressions, map data and the like,and a RAM that stores data temporarily.

FIG. 4 is an image diagram illustrating a damping characteristic oftorsional vibration by the damper device 11. In FIG. 4, the abscissaaxis represents the vibration frequency, i.e. the frequency, oftorsional vibration, and the ordinate axis represents drive systemsensitivity, being the vibration acceleration level of torsionalvibration. In FIG. 4, a characteristic line L1 represented by a dottedline denotes a damping characteristic of torsional vibration outputtedfrom the second ring gear R2, and a characteristic line L2 representedby a dot-chain line denotes a damping characteristic of torsionalvibration outputted from the sun gear S.

As indicated by the characteristic line L1 of FIG. 4, torsionalvibration is amplified at a low frequency region, but torsionalvibration is damped at a medium-high frequency region, in a case wherethe first clutch CL1 is engaged and the engine torque is outputted fromthe second ring gear R2. Specifically, the rotation phase of thecrankshaft 21 and the rotation phase of the first ring gear R1 have thesame direction at the low frequency region that is below a resonancepoint (natural frequency) F1 of a vibration system 28 that comprises thespring 22, the first ring gear R1 and the inertia member 23. That is,the rotation phase of the crankshaft 21 and the rotation phase of thesecond ring gear R2 have the same direction; as a result, the crankshaft21 and the second ring gear R2 vibrate at the same phase, and torsionalvibration is amplified, in a case where the engine torque is outputtedfrom the second ring gear R2 at the low frequency region. By contrast,the rotation phase of the crankshaft 21 and the rotation phase of thefirst ring gear R1 have opposite directions at the medium-high frequencyregion beyond the resonance point F1 of the vibration system 28. Therotation phase of the crankshaft 21 and the rotation phase of the secondring gear R2 have opposite directions; as a result, the crankshaft 21and the second ring gear R2 vibrate at opposite phases, and torsionalvibration is damped, in a case where the engine torque is outputted fromthe second ring gear R2 at the medium-high frequency region.

As indicated by the characteristic line L2 in FIG. 4, the amplificationamount of torsional vibration is curtailed to a greater degree than forthe characteristic line L1, at the low frequency region, and the dampingamount is curtailed to a greater degree than for the characteristic lineL1, at the medium-high frequency region, in a case where the secondclutch CL2 is engaged and the engine torque is outputted from the sungear S. As described above, the rotation phase of the crankshaft 21 andthe rotation phase of the first ring gear R1 have the same direction atthe low frequency region that is below the resonance point (naturalfrequency) F1 of the vibration system 28. That is, the rotation phase ofthe crankshaft 21 and the rotation phase of the sun gear S have oppositedirections; as a result, the amplification amount of torsional vibrationis curtailed to a greater degree as compared with that of thecharacteristic line L1, in a case where the engine torque is outputtedfrom the sun gear S, at the low frequency region. By contrast, therotation phase of the crankshaft 21 and the rotation phase of the firstring gear R1 have opposite directions at the medium-high frequencyregion beyond the resonance point F1 of the vibration system 28. Thatis, the rotation phase of the crankshaft 21 and the rotation phase ofthe sun gear S have the same direction; as a result, the damping amountof torsional vibration is curtailed to a greater degree as compared withthat of the characteristic line L1, in a case where the engine torque isoutputted from the sun gear S, at the medium-high frequency region.

As illustrated in FIG. 4, a difference in damping characteristic oftorsional vibration arises thus between an instance where the enginetorque is outputted from the second ring gear R2, and in an instancewhere the engine torque is outputted from the sun gear S. Specifically,the distribution ratios of the engine torques T1 and T2 that aredistributed over the first input path 24 and the second input path 25are different between an instance where the engine torque is outputtedfrom the second ring gear R2 and an instance where the engine torque isoutputted from the sun gear S. A difference arises as a result in thedamping characteristic of torsional vibration. In the configurationillustrated in the figure, in particular, the rotation directions of thesecond ring gear R2 and the sun gear S are different in a case where thecompound pinion gear CP rotates while the spring 22 is stretched andcompressed. As a result, a significant difference arises in the dampingcharacteristic of torsional vibration.

The damping characteristic can be thus modified through switchingbetween the output paths 26 and 27. Accordingly, the control unit 30switches the first clutch CL1 or the second clutch CL2 to the engagedstate on the basis of the frequency of torsional vibration, i.e. on thebasis of engine revolutions. FIG. 5 is an explanatory diagramillustrating a control state of the first clutch CL1 and the secondclutch CL2. As illustrated in FIG. 5, the second clutch CL2 is engaged,and the engine torque is outputted from the sun gear S, at a frequencyregion below a frequency F2 at which the characteristic lines L1 and L2intersect, i.e. at a region at which engine revolutions are belowreference revolutions corresponding to the frequency F2 of torsionalvibration. On the other hand, the first clutch CL1 is engaged, and theengine torque is outputted from the second ring gear R2, at a frequencyregion beyond the frequency F2, i.e. at a region at which enginerevolutions exceed the reference revolutions corresponding to thefrequency F2 of torsional vibration.

A good damping characteristic can be obtained over the entire frequencyregion, as illustrated by the bold line in FIG. 5, through switching ofthe clutches CL1 and CL2 to the engaged state, on the basis of enginerevolutions. The torsional vibration of the engine 12 can be suppressedthereby, and as a result, vehicle quality can be enhanced throughsuppression of vibration and noise. The load that acts on thetransmission 13 can be reduced, and durability of the transmission 13can be enhanced, through curtailment of the torsional vibration of theengine 12. By virtue of the curtailed vibration of the engine 12, thenumber of cylinders of the engine 12 can be reduced, the use region ofengine revolutions can be lowered, and the fuel efficiency of thevehicle can be enhanced.

In the instance illustrated in the figure, the carrier C is set tofunction as a first input element, and the first ring gear R1 is set tofunction as a second input element, but the implementation is notlimited thereto. For instance, the first ring gear R1 may be connecteddirectly with the crankshaft 21, and the carrier C may be connected tothe crankshaft 21 via the spring 22. In this case, the first ring gearR1 functions as the first input element, and the carrier C functions asthe second input element. By providing the sun gear that meshes with thefirst pinion gear P1, the sun gear may be set to function as the firstinput element (or second input element). Thus, the first ring gear R1may be set to function as the second input element (or first inputelement), and the carrier C may be set to function as the second inputelement (or first input element), in a case where the sun gear thatmeshes with the first pinion gear P1 is set to function as the firstinput element (or second input element). In the instance illustrated inthe figure, the second ring gear R2 is set to function as the firstoutput element, and the sun gear S is set to function as the secondoutput element, but the implementation is not limited thereto. Thecarrier C may be set to function as the first output element (or secondoutput element) upon disconnection from the crankshaft 21, in a casewhere, for instance, the sun gear that meshes with the first pinion gearP1 is set to function as the first input element (or second inputelement) and the first ring gear R1 is set to function as the secondinput element (or first input element), as described above.

In the description above, the second ring gear R2 is set to function asthe first output element, and the sun gear S is set to function as thesecond output element, as a result of which the first output element andthe second output element are caused to rotate in opposite directionsupon rotation of the compound pinion gear CP, but the implementation ofthe present invention is not limited thereto.

For instance, a planetary gear train made up of the second ring gear R2,the second pinion gear P2 and the sun gear S may be configured in theform of a double pinion-type planetary gear train, so that, as a result,the first output element and the second output element are caused torotate in the same direction upon rotation of the compound pinion gearCP. In this case as well, adjusting the number of teeth of therespective gears that make up the torque distribution mechanism 20allows modifying the distribution ratio of the above-described enginetorques T1 and T2, between an instance where the engine torque isoutputted from the first output element and an instance where the enginetorque is outputted from the second output element, and allows impartinga difference in the damping characteristic of torsional vibration.

FIG. 6 is a schematic diagram illustrating a power unit 41 comprising adamper device 40 being a second implementation of the present invention.In FIG. 6, members that are illustrated in FIG. 1 and members identicalto those illustrated in FIG. 1 are denoted by identical referencesymbols, and a recurrent description thereof will be omitted.

As illustrated in FIG. 6 and FIG. 7, the damper device 40 comprises atorque distribution mechanism (planetary gear mechanism) 42 made up of acompound planetary gear train. The torque distribution mechanism 42comprises the carrier (first input element) C connected with thecrankshaft 21, and an input ring gear (second input element) Riconnected to the crankshaft 21 via a spring (elastic member) 22. Theinertia member 23 having a predetermined mass is fixed to the input ringgear Ri that is connected to the crankshaft 21 via the spring 22. Thetorque distribution mechanism 42 further comprises a first ring gear(first output element, gear) R1 a connected to the transmission 13, anda second ring gear (second output element, gear) R2 a connected to thetransmission 13. A compound pinion gear CPa is rotatably provided on thecarrier C. The compound pinion gear CPa is made up of an input piniongear Pi, a first pinion gear P1 a and a second pinion gear P2 a. Theinput pinion gear Pi meshes with the input ring gear Ri, the firstpinion gear P1 a meshes with the first ring gear R1 a, and the secondpinion gear P2 a meshes with the second ring gear R2 a. The number ofteeth of the first ring gear R1 a is greater than the number of teeth ofthe second ring gear R2 a. That is, the number of teeth of the firstring gear R1 a is different from the number of teeth of the second ringgear R2 a.

As described above, the torque distribution mechanism 42 is providedwith the two input paths 24 and 25, through which the engine torque isinputted and the two output paths 26 and 27 through which the enginetorque is outputted. Specifically, the torque distribution mechanism 42is provided with a first input path 24 through which the engine torqueis inputted to the carrier C, and with a second input path 25 throughwhich the engine torque is inputted to input ring gear Ri via the spring22. By virtue of the spring 22 being provided thus in the second inputpath 25, the spring 22 can as a result be stretched and compressed inresponse to the torsional vibration of the engine 12, and the carrier Cand the input ring gear Ri can be caused to rotate relatively to eachother. The torque distribution mechanism 42 is also provided with thefirst output path 26 through which the engine torque is outputted fromthe first ring gear R1 a, and with the second output path 27 throughwhich the engine torque is outputted from the second ring gear R2 a. Theinput paths 24, 25 and the output paths 26 and 27 are made up ofrotating shafts, hub members, drum members and so forth.

The first clutch CL1 that is switched between the engaged state and thereleased state is provided between the first ring gear R1 a and thetransmission 13. The first ring gear R1 a becomes connected to thetransmission 13 through switching of the first clutch CL1 to the engagedstate, and the first ring gear R1 a becomes disconnected from thetransmission 13 through switching of the first clutch CL1 to thereleased state. In a case where the first clutch CL1 is switched to theengaged state, as illustrated in FIG. 8A, the engine torques T1 and T2that are distributed over the first input path 24 and the second inputpath 25 are combined via the torque distribution mechanism 42, andthereafter, the engine torques T1, T2 are outputted through the firstring gear R1 a and through first output path 26 to the transmission 13.Herein, the distribution ratio between the engine torque T1 and theengine torque T2 for canceling out the torque variation of the enginetorque T1 is set on the basis of the number of teeth of the input ringgear Ri, the input pinion gear Pi, the first ring gear R1 a and thefirst pinion gear P1 a.

Similarly, the second clutch CL2 that is switched between the engagedstate and the released state is provided between the second ring gear R2a and the transmission 13. The second ring gear R2 a becomes connectedto the transmission 13, through switching of the second clutch CL2 tothe engaged state, and the second ring gear R2 a becomes disconnectedfrom the transmission 13 through switching of the second clutch CL2 tothe released state. In a case where the second clutch CL2 is switched tothe engaged state, as illustrated in FIG. 8B, the engine torques T1, T2that are distributed over the first input path 24 and the second inputpath 25 are combined via the torque distribution mechanism 42, andthereafter, the engine torques T1, T2 are outputted from the second ringgear R2 a and the second output path 27 to the transmission 13. Herein,the distribution ratio between the engine torque T1 and the enginetorque T2 for canceling out the torque variation of the engine torque T1is set on the basis of the number of teeth of the input ring gear Ri,the input pinion gear Pi, the second ring gear R2 a and the secondpinion gear P2 a.

As illustrated in FIG. 6, the control unit 30 that functions as a clutchcontroller is provided in the power unit 41, with a view to controllingthe first clutch CL1 and the second clutch CL2 of the damper device 40.The power unit 41 is provided with the valve unit 31 that comprises aplurality of electromagnetic valves, and with the oil pump 32 that pumpshydraulic oil towards the valve unit 31. The engine revolutions sensor33 that detects a rotational speed (hereafter notated as enginerevolutions) of the crankshaft 21 is connected to the control unit 30.On the basis of engine revolutions detected by the engine revolutionssensor 33, the control unit 30 selects the clutches CL1, CL2 that areswitched to the engaged state, and outputs a control signal to the valveunit 31. On the basis of engine revolutions, specifically, the controlunit 30 switches the first clutch CL1 or the second clutch CL2 to theengaged state, and selects thereby the control unit 30 selects theoutput paths 26 and 27 for extracting the engine torque. The controlunit 30 is made up of, for instance, a CPU that computes control signalsand the like, a ROM that stores a control program, arithmeticexpressions, map data and the like, and a RAM that stores datatemporarily.

FIG. 9 is an image diagram illustrating a damping characteristic oftorsional vibration by the damper device 40. In FIG. 9, the abscissaaxis represents the vibration frequency, i.e. the frequency, oftorsional vibration, and the ordinate axis represents drive systemsensitivity, being the vibration acceleration level of torsionalvibration. In FIG. 9, a characteristic line L1 represented by a dottedline denotes a damping characteristic of torsional vibration outputtedfrom the first ring gear R1 a, and a characteristic line L2 representedby a dot-chain line denotes a damping characteristic of torsionalvibration outputted from the second ring gear R2 a.

As indicated by the characteristic line L1 of FIG. 9, torsionalvibration is amplified from a low frequency region over to a highfrequency region, as denoted by the reference symbol A1, and torsionalvibration is damped thereafter as denoted by the reference symbol B1, ina case where the engine torque is outputted from the first ring gear R1a. That is, the rotation phases of the crankshaft 21 and of the inputring gear Ri have the same direction, at a frequency region that isbelow a resonance point (natural frequency) of the vibration system 28that comprises the spring 22, the input ring gear Ri and the inertiamember 23. As a result, the crankshaft 21 and the input ring gear Rivibrate at the same phase, and torsional vibration is amplified. Therotation phases of the crankshaft 21 and of the input ring gear Ri haveopposite directions at a frequency region beyond the resonance point ofthe vibration system 28. As a result, the crankshaft 21 and the inputring gear Ri vibrate in opposite phases, and torsional vibration isdamped. As indicated by the characteristic line L2 of FIG. 9, similarly,torsional vibration is amplified, as denoted by the reference symbol A2,from a low frequency region over to a high frequency region, andtorsional vibration is damped thereafter as denoted by the referencesymbol B2, in a case where the engine torque is outputted from thesecond ring gear R2 a.

As denoted by the characteristic lines L1, L2 in FIG. 9, a difference indamping characteristic of torsional vibration arises between an instancewhere the engine torque is outputted from the first ring gear R1 a andan instance where the engine torque is outputted from the second ringgear R2A. Specifically, the torsional vibration that is transmitted fromthe damper device 40 to the transmission 13 is a combination of thetorsional vibration of the engine torque T1 that is inputted to thecarrier C through the first input path 24, and the torsional vibrationof the engine torque T2 that is inputted to the input ring gear Rithrough the second input path 25. The amplitude and phase of vibrationare mutually dissimilar between the torsional vibration of the enginetorque T1 and the torsional vibration of the engine torque T2 forcanceling out the torsional vibration of the engine torque T1.Accordingly, the torsional vibration outputted from the damper device40, i.e. the torsional vibration at the time where the engine torques T1and T2 are combined, can be caused to vary through modification of thedistribution ratio of the engine torques T1 and T2.

As described above, the distribution ratio of the engine torques T1 andT2 at a time where the first clutch CL1 is engaged is determined on thebasis of the number of teeth of the input ring gear Ri, the input piniongear Pi, the first ring gear R1 a and the first pinion gear P1 a. Thedistribution ratio of the engine torques T1 and T2 at a time where thesecond clutch CL2 is engaged is determined on the basis of the number ofteeth of the input ring gear Ri, the input pinion gear Pi, the secondring gear R2 a and the second pinion gear P2 a. Herein, the number ofteeth of the first ring gear R1 a is different from that of the secondring gear R2A. It becomes possible as a result to modify thedistribution ratio of the engine torques T1, T2 between an instancewhere the first clutch CL1 is engaged and an instance where the secondclutch CL2 is engaged. That is, the damping characteristic of torsionalvibration can be modified as a result of switching between the outputpaths 26, 27 through control of the clutches CL1 and CL2.

The damping characteristic can be thus modified through switchingbetween the output paths 26 and 27. As a result, the control unit 30switches the first clutch CL1 or the second clutch CL2 to the engagedstate on the basis of the frequency of torsional vibration, i.e. on thebasis of engine revolutions. FIG. 10 is an explanatory diagramillustrating a control state of the first clutch CL1 and the secondclutch CL2. As illustrated in FIG. 10, characteristic lines L1 and L2intersect each other at frequencies F1 and F2. The second clutch CL2 isengaged, and the engine torque is outputted from the second ring gear R2a, at a frequency region below frequency F1, i.e. at a region at whichengine revolutions are below revolutions corresponding to the frequencyF1. The first clutch CL1 is engaged, and the engine torque is outputtedfrom the first ring gear R1 a, at a frequency region ranging fromfrequency F1 to frequency F2, i.e. at a region at which enginerevolutions lie within a revolutions range corresponding to frequenciesF1 to F2. The second clutch CL2 becomes engaged again, and the enginetorque is outputted from the second ring gear R2 a, at a frequencyregion beyond frequency F2, i.e. at a region at which engine revolutionsexceed the revolutions corresponding to the frequency F2 of torsionalvibration.

A good damping characteristic can be obtained over the entire frequencyregion, as illustrated by the bold line in FIG. 10, through switching ofthe clutches CL1 and CL2 to the engaged state, on the basis of enginerevolutions. That is, a good damping characteristic can be obtained overthe entire frequency region, in such a manner that inflection points A1,A2 on the vibration amplification side are excluded and inflectionpoints B1 and B2 on the vibration damping side are included. Thetorsional vibration of the engine 12 can be suppressed thereby, and as aresult, vehicle quality can be enhanced through suppression of vibrationand noise. Further, suppression of torsional vibration of the engine 12allows mitigating the load that acts on the transmission 13, and allowsenhancing the durability of the transmission 13. Likewise, suppressionof torsional vibration of the engine 12 allows reducing the number ofcylinders of the engine 12 and lowering the use region of enginerevolutions, while enhancing the fuel efficiency of the vehicle.

In the instance illustrated in the figure, the carrier C is set tofunction as a first input element and the input ring gear Ri is set tofunction as a second input element, but the implementation is notlimited thereto. For instance, the input ring gear Ri may be connecteddirectly with the crankshaft 21, and the carrier C may be connected tothe crankshaft 21 via the spring 22. In this case, the input ring gearRi functions as the first input element, and the carrier C functions asthe second input element. By providing the sun gear that meshes with theinput pinion gear Pi, the sun gear may be set to function as the firstinput element (or second input element). The input ring gear Ri may beset to function as the second input element (or first input element),and the carrier C may be set to function as the second input element (orfirst input element), in a case where the sun gear that meshes with theinput pinion gear Pi is set to function as the first input element (orsecond input element).

In the description of the first implementation of the present invention,the torque distribution mechanism 20 is made up of a compound planetarygear that comprises the compound pinion gear CP, but the implementationis not limited thereto, and the torque distribution mechanism 20 may bemade up of a simple planetary gear train. FIG. 11 is a schematic diagramillustrating a power unit 51 comprising a damper device 50 being anotherimplementation of the present invention. In FIG. 11, members that areillustrated in FIG. 1 and members identical to those illustrated in FIG.1 are denoted by identical reference symbols, and a recurrentdescription thereof will be omitted.

As illustrated in FIG. 11, the damper device 50 comprises a torquedistribution mechanism (planetary gear mechanism) 52 made up of a simpleplanetary gear train. The torque distribution mechanism 52 comprises acarrier (first input element) Cb connected to the crankshaft 21. Thetorque distribution mechanism 52 comprises a ring gear (second inputelement, first output element) Rb one side whereof is connected to thecrankshaft 21 via the spring 22, the other side being connected to thetransmission 13. The torque distribution mechanism 42 comprises a sungear (second output element) Sb connected to the transmission 13. Apinion gear Pb that meshes with the ring gear Rb and the sun gear Sb isrotatably supported on the carrier Cb. The first clutch CL1 that isswitched between the engaged state and the released state is providedbetween the ring gear Rb and the transmission 13. The second clutch CL2that is switched between the engaged state and the released state isprovided between the sun gear Sb and the transmission 13. Thus, adamping effect such as the one of the above-described damper device 11can be achieved by switching the first clutch CL1 or the second clutchCL2 to the engaged state, on the basis of engine revolutions, also in acase where the second input element and the first output element areconfigured integrally in the form of one ring gear Rb that meshes withthe pinion gears Pb.

FIG. 12 is an image diagram illustrating a damping characteristic oftorsional vibration by the damper device 50. In FIG. 12, acharacteristic line La represented by a dotted line denotes a dampingcharacteristic of torsional vibration outputted from a ring gear 42 rthat is connected to the crankshaft 21 via the spring 22, and acharacteristic line Lb represented by a dot-chain line denotes a dampingcharacteristic of torsional vibration outputted from the sun gear Sb.FIG. 13 is an explanatory diagram illustrating a control state of thefirst clutch CL1 and the second clutch CL2.

As denoted by the characteristic lines La, Lb in FIG. 12, a differencein damping characteristic of torsional vibration arises between aninstance where the engine torque is outputted from the ring gear Rb andan instance where the engine torque is outputted from the sun gear Sb.That is, a better damping characteristic of torsional vibration can beachieved in a case where the engine torque is outputted from the sungear Sb through engagement of the second clutch CL2, at a low-mediumfrequency region. At a high frequency region, by contrast, a betterdamping characteristic of torsional vibration can be achieved in a casewhere the engine torque is outputted from the ring gear Rb throughengagement of the first clutch CL1.

As illustrated in FIG. 13, specifically, the second clutch CL2 isengaged, in order for the engine torque to be outputted from the sungear Sb, at a frequency region that is below a frequency F3 at which thecharacteristic lines La, Lb intersect, namely a region at which enginerevolutions are below reference revolutions that correspond to thefrequency F3 of torsional vibration. On the other hand, the first clutchCL1 is engaged in order for the engine torque to be outputted from thering gear Rb, at a frequency region that exceeds the frequency F3, i.e.at a region at which engine revolutions exceed the reference revolutionscorresponding to the frequency F3 of torsional vibration. A good dampingcharacteristic can be obtained over the entire frequency region, asillustrated by the bold line in FIG. 13, through switching of theclutches CL1, CL2 to the engaged state, on the basis of enginerevolutions.

In the description of the second implementation of the presentinvention, the first ring gear R1 a is set to function as the firstoutput element, and the second ring gear R2 a is set to function as thesecond output element, but the implementation is not limited thereto.FIG. 14 is a schematic diagram illustrating a power unit 61 comprising adamper device 60 being another implementation of the present invention.In FIG. 14, members that are illustrated in FIG. 6 and members identicalto those illustrated in FIG. 6 are denoted by identical referencesymbols, and a recurrent description thereof will be omitted.

As illustrated in FIG. 14, the damper device 60 comprises a torquedistribution mechanism (planetary gear mechanism) 62. The torquedistribution mechanism 62 comprises a first sun gear (first outputelement, gear) S1 c connected to the transmission 13. The first sun gearSic meshes with the first pinion gear P1 a of the compound pinion gearCPa. The torque distribution mechanism 62 comprises a second sun gear(second output element, gear) S2 c connected to the transmission 13. Thesecond sun gear S2 c meshes with the second pinion gear P2 a of thecompound pinion gear CPa. The first clutch CL1 that is switched betweenthe engaged state and the released state is provided between the firstsun gear Sic and the transmission 13. The second clutch CL2 that isswitched between the engaged state and the released state is providedbetween the second sun gear S2 c and the transmission 13. Further, thenumber of teeth of the first sun gear S1 is different from the number ofteeth of the second sun gear S2 c.

An effect identical to that of the above-described damper device 40 canbe achieved by switching the first clutch CL1 or the second clutch CL2to the engaged state, on the basis of engine revolutions, also in a casewhere the first sun gear S1 is set to function as the first outputelement the second sun gear S2 is set to function as the second outputelement. Specifically, the number of teeth of the first sun gear S1 c isdifferent from the second sun gear S2 c; as a result, it becomespossible to modify the distribution ratio of the engine torques T1, T2between an instance where the first clutch CL1 is engaged and aninstance where the second clutch CL2 is engaged. Thus, the dampingcharacteristic of torsional vibration can be modified as a result ofswitching between the output paths 26 and 27 through control of theclutches CL1 and CL2. It becomes accordingly possible to achieve a gooddamping characteristic over the entire frequency region.

In the description above, the compound pinion gear CPa comprising threepinion gears Pi, P1 a and P2 a is resorted to, but the implementation isnot limited thereto, and a compound pinion gear may be used thatcomprises two pinion gears. FIG. 15 is a schematic diagram illustratinga power unit 71 comprising a damper device 70 being anotherimplementation of the present invention. In FIG. 15, members that areillustrated in FIG. 6 and members identical to those illustrated in FIG.6 are denoted by identical reference symbols, and a recurrentdescription thereof will be omitted.

As illustrated in FIG. 15, the damper device 70 comprises a torquedistribution mechanism (planetary gear mechanism) 72. The torquedistribution mechanism 72 comprises a carrier (first input element) Cdconnected with the crankshaft 21. The torque distribution mechanism 72comprises a first ring gear (second input element, first output element,gear) R1 d one side whereof is connected to the crankshaft 21 via thespring 22, the other side being connected to the transmission 13. Thetorque distribution mechanism 72 comprises a second ring gear (secondoutput element, gear) R2 d that is connected to the transmission 13. Acompound pinion gear CPd that comprises two pinion gears P1 d, P2 d isrotatably supported on the carrier Cd. The first pinion gear P1 d of thecompound pinion gear CPd meshes with the first ring gear R1 d, and thesecond pinion gear P2 d of the compound pinion gear CPd meshes with thesecond ring gear R2 d. The first clutch CL1 that is switched between theengaged state and the released state is provided between the first ringgear Rid and the transmission 13. The second clutch CL2 that is switchedbetween the engaged state and the released state is provided between thesecond ring gear R2 d and the transmission 13. Further, the number ofteeth of the first ring gear Rid is different from the number of teethof the second ring gear R2 d.

An effect identical to that of the above-described damper device 11 canbe achieved by switching the first clutch CL1 or the second clutch CL2to the engaged state, on the basis of engine revolutions, also in a casewhere the second input element and the first output element areintegrally configured in the form of one first ring gear R1 d thatmeshes with the first pinion gear P1 d. That is, a dampingcharacteristic can be achieved through combination of the inertia member23 and the spring 22, in a case where the first clutch CL1 is engaged,while a damping characteristic such that the distribution ratio of theengine torques T1 and T2 is modified can be achieved in a case where thesecond clutch CL2 is engaged. Thus, the damping characteristic oftorsional vibration can be modified as a result of switching between theoutput paths 26, 27 through control of the clutches CL1 and CL2. Itbecomes accordingly possible to achieve a good damping characteristicover the entire frequency region.

The present invention is not limited to the above implementations, and,needless to say, may accommodate various modifications without departingfrom the spirit and scope of the invention. In the above description,the engagement region of the first clutch CL1 and the engagement regionof the second clutch CL2 are divided along one or two frequencies asboundaries, but the present invention is not limited thereto, and theengagement region of the first clutch CL1 and the engagement region ofthe second clutch CL2 may be divided along a plurality of frequencies asboundaries, depending on the damping characteristic to be obtained. Inthe description above, the torque distribution mechanisms 20, 42, 52 and72 are made up of planetary gear trains, but the invention is notlimited thereto, and the torque distribution mechanisms may be made upof bevel gears or the like.

The first clutch CL1 and the second clutch CL2 are not limited tohydraulic clutches that are hydraulically switched between the engagedstate and the released state, and may be electromagnetic clutches thatare switched between the engaged state and the released state byelectromagnetic forces. The first clutch CL1 and the second clutch CL2may be friction clutches or meshing clutches. In the above description,the elastic member is exemplified in the form of the spring 22, but thepresent invention is not limited thereto, and a rubber member may beused as an elastic member.

The transmission 13 may be a manual transmission, acontinuously-variable transmission, or a planetary gear-type or parallelshaft-type automatic transmission. A torque converter may be providedbetween each of the damper devices 11, 40, 50, 60 and 70 and thetransmission 13, and a starting clutch may be provided between each ofthe damper device 11, 40, 50, 60 and 70 and the transmission 13. Thedamper devices 11, 40, 50, 60 and 70 each may be built into the case ofthe torque converter. The engine 12 is not limited to a gasoline engine,and may be a diesel engine or the like.

1. A damper device disposed between an engine and a transmission, thedamper device comprising: a torque distribution mechanism including: afirst input element connected to the engine; a second input elementconnected to the engine via an elastic member; a first output elementconnected to the transmission; and a second output element connected tothe transmission, wherein after combining a first torque output from thefirst input element and a second torque output from the second inputelement, the combined torque is output to one of the first outputelement and the second output element; a first clutch that is disposedbetween the first output element and the transmission, and that isswitched between an engaged state of connecting the first output elementto the transmission and a released state of disconnecting the firstoutput element from the transmission; and a second clutch that isdisposed between the second output element and the transmission, andthat is switched between an engaged state of connecting the secondoutput element to the transmission and a released state of disconnectingthe second output element from the transmission, wherein the firstoutput element and the second output element are gears, and the numberof teeth of the first output element is different from the number ofteeth of the second output element.
 2. The damper device according toclaim 1, wherein the numbers of teeth of the first output element andthe second output element are set to be dissimilar, such that adistribution ratio of engine torque that is inputted to the first inputelement and the second input element when the first clutch is switchedto the engaged state is made different from a distribution ratio ofengine torque that is inputted to the first input element and the secondinput element when the second clutch is switched to the engaged state.3. The damper device according to claim 1, further comprising a clutchcontroller for switching the first clutch or the second clutch to theengaged state on the basis of a rotational speed of the engine.
 4. Thedamper device according to claim 2, further comprising a clutchcontroller for switching the first clutch or the second clutch to theengaged state on the basis of a rotational speed of the engine.
 5. Thedamper device according to claim 1, wherein the torque distributionmechanism comprises a planetary gear mechanism including a compoundpinion gear; the first output element comprises a first ring gearmeshing with a first pinion gear of the compound pinion gear; and thesecond output element comprises a second ring gear meshing with a secondpinion gear of the compound pinion gear.
 6. The damper device accordingto claim 2, wherein the torque distribution mechanism comprises aplanetary gear mechanism including a compound pinion gear; the firstoutput element comprises a first ring gear meshing with a first piniongear of the compound pinion gear; and the second output elementcomprises a second ring gear meshing with a second pinion gear of thecompound pinion gear.
 7. The damper device according to claim 3, whereinthe torque distribution mechanism comprises a planetary gear mechanismincluding a compound pinion gear; the first output element comprises afirst ring gear meshing with a first pinion gear of the compound piniongear; and the second output element comprises a second ring gear meshingwith a second pinion gear of the compound pinion gear.
 8. The damperdevice according to claim 4, wherein the torque distribution mechanismcomprises a planetary gear mechanism including a compound pinion gear;the first output element comprises a first ring gear meshing with afirst pinion gear of the compound pinion gear; and the second outputelement comprises a second ring gear meshing with a second pinion gearof the compound pinion gear.
 9. The damper device according to claim 1,wherein the torque distribution mechanism comprises a planetary gearmechanism including a compound pinion gear; the first output elementcomprises a first sun gear meshing with a first pinion gear of thecompound pinion gear; and the second output element comprises a secondsun gear meshing with a second pinion gear of the compound pinion gear.10. The damper device according to claim 2, wherein the torquedistribution mechanism comprises a planetary gear mechanism including acompound pinion gear; the first output element comprises a first sungear meshing with a first pinion gear of the compound pinion gear; andthe second output element comprises a second sun gear meshing with asecond pinion gear of the compound pinion gear.
 11. The damper deviceaccording to claim 3, wherein the torque distribution mechanismcomprises a planetary gear mechanism including a compound pinion gear;the first output element comprises a first sun gear meshing with a firstpinion gear of the compound pinion gear; and the second output elementcomprises a second sun gear meshing with a second pinion gear of thecompound pinion gear.
 12. The damper device according to claim 3,wherein the torque distribution mechanism comprises a planetary gearmechanism including a compound pinion gear; the first output elementcomprises a first sun gear meshing with a first pinion gear of thecompound pinion gear; and the second output element comprises a secondsun gear meshing with a second pinion gear of the compound pinion gear.13. The damper device according to claim 5, wherein the compound piniongear is rotatably supported by the first input element or the secondinput element.
 14. The damper device according to claim 9, wherein thecompound pinion gear is rotatably supported by the first input elementor the second input element.